LATHE OPERATIONS - OD1645 - LESSON 1/TASK 3
of threads per inch the tool is to cut. One can see that the size of this
flat on the tool point will vary, depending upon the thread per inch to be
machined.
FIGURE 50.
ACME THREAD GAGE.
(2) After grinding the tool, set the compound rest to one-half the
included angle of the thread (14 1/2) to the right of the vertical
centerline of the machine. Mount the tool in the holder or toolpost so that
the top of the tool is on the axis or centerline of the workpiece. The tool
is set square to the work, using the thread gage as shown in figure 50.
This thread is cut using the compound feed. The depth to which one feeds
the compound to obtain the total thread depth is determined by the formula
given and illustrated in figure 41 on page 108. The remainder of the Acme
thread cutting operation is the same as the V-threading operation previously
described. The compound should be fed into the workpiece only at 0.002 inch
to 0.003 inch per cut until the desired depth of thread is obtained.
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